Field
Exemplary embodiments of the present invention relate to a display device including a touch sensing sensor.
Discussion of the Background
A display device such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display, an electrophoretic display, etc. typically includes a field generating electrode and an electro-optical active layer.
For example, the OLED display may include an organic emission layer as the electro-optical active layer.
The field generating electrode is connected to switching elements such as a thin film transistor and the like to be applied with a data signal, and the electro-optical active layer converts the data signal into an optical signal to display an image.
When a heavy and fragile glass substrate is used in a display panel of the display device, there are some limitations in the portability, size, and weight of the display.
Accordingly, recently, a flexible display device using a plastic substrate, which is light, strong, impact-resistant, and flexible, has been actively developed as a substrate for the display panel.
The display device may include a touch sensor allowing a user to easily interact with the device, in addition to displaying an image.
Touch sensing is used to determine touch information, such as whether an object approaches or contacts a screen, and its touch position by sensing changes in pressure, charges, light, and the like that may be applied to the screen of the display device when a user writes characters or draws figures by approaching or touching the screen using a finger or a touch pen.
The display device may receive an image signal based on the contact information to display an image.
Touch sensing may be implemented by a touch sensing sensor.
The touch sensing sensor may be classified into various types such as a resistive type, a capacitive type, an electromagnetic type (EM), an optical type, etc.
For example, in the resistive type of touch sensor, two electrodes that face each other and are separated from each other may contact each other due to pressure from an external object.
When the two electrodes contact each other, a change in voltage caused by a change in resistance at the touch position may be detected such that the touch position and the like are determined.
The capacitive type of touch sensing sensor includes a sensing capacitor including a plurality of sensing electrodes for transmitting a detection signal, and detects a change in capacitance of the sensing capacitor and/or an amount of charges that is caused when a conductor such as a finger approaches the touch sensing sensor, thereby determining whether or not touch occurs and the touch position.
The capacitive type of touch sensing sensor may include a plurality of touch electrodes disposed in the contact sensing area and signal-transmitting wires connected to the touch electrodes.
The signal-transmitting wires may transmit a sensing input signal to the touch electrodes, or may transmit a sensing output signal of the touch electrodes to a sensing signal controller.
In a flexible display device, the touch sensing sensor may be formed in a separate touch screen panel and may be attached to the flexible display device to be provided as an add-on cell type.
When a touch panel is attached to a display device, processes of manufacturing the touch panel and then attaching the touch panel on the display device may be added, thereby deteriorating yields and increasing cost.
In addition, an adhesive layer may be disposed between the touch panel and the display device or on the touch panel to attach the touch panel on the display device and to fix it thereon, which may cause a thickness of the display device to increase.
Further, the attached touch panel may deteriorate transmittance, increase reflectance, and increase haze.
Further, metal electrodes included in a touch sensing sensor of the touch panel attached to the outside of the display device may corrode to cut off wires.
Further, when a flexible display device attached to the touch panel is bent, its durability may deteriorate to cause defects.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.